PPP Multilink over MPLS - T1 to E1

Answered Question
May 8th, 2010

A company that I am doing some work for has an MPLS VPN between their offices in the US and Europe.  They are having some Video Conference QoS issues and I believe one of their problems related to the differences in the circuit bandwidth between the two sites.

What I want to do is decrease MAX rate of the dual bonded E1s to match that of the dual T1s so that the routers QoS policy calculations are the same at both sites.

Would it be better to use rate-limit or traffic-shape here?  Also, should this be applied to the multilink interface or the individual interfaces?

Any other recommendations would be appreciated as well.

Thanks,

-Jeff

I have this problem too.
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Correct Answer by Paolo Bevilacqua about 6 years 7 months ago

There is absolutely no need to decrease speed on the E1 side, nor shape traffic.

What is needed, is a complete analysis of the problem, done by an expert and in collboration with the SP.

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Giuseppe Larosa Sat, 05/08/2010 - 01:00

Hello Jeff,

use a policy-map using the shape action this allows to invoke a child policy that implements queueing

the parent policy has to be applied to the only L3 object that is the multilink interface

something like:

policy-map shape_to_2T1

class class-default

shape 2800000

service child-queues

policy-map child-queues

class voice

priority 400

class videoconf

bandwidth 1000

class dataplus

bandwidth 300

class class-default

fair-queue

note: shaping commands use bps,  priority and bandwidth use kbps

int multi1

service out shape_to_2T1

Hope to help

Giuseppe

Correct Answer
Paolo Bevilacqua Sat, 05/08/2010 - 03:17

There is absolutely no need to decrease speed on the E1 side, nor shape traffic.

What is needed, is a complete analysis of the problem, done by an expert and in collboration with the SP.

jeffkolbash Sat, 05/08/2010 - 11:14

OK... Can you please explain to me why you think rate limiting the E1 side would not be  beneficial?

I have been called in by the customer to  work with the service provider on this issue.  The SP has failed to  deliver the customer a satisfactory product for over 6 months now.  All  routers are SP managed.  After reviewing all of the router  configurations there are some things that I call into question.  One of  them is the imbalance on the E1side of the pipe.

-Jeff

Paolo Bevilacqua Sat, 05/08/2010 - 13:24

Because such a small unbalance will not affect a properly configured QoS.

However if SP is not collaborating all bets are off and you may have better resuslts with a good VPN instead.

jeffkolbash Thu, 08/11/2011 - 13:16

I know it has been quite some time since the original post.  Just wanted to follow up with what was happening here. 

The company was running for a couple of years on a single T1 from Sprint.  When Sprint ordered the 2nd T1 for the bonded link it was not over the same physical path as the original circuit.  The result was a difference in latency of about 30ms between the 2 circuits.  Once the circuit was moved to follow the same path, everything worked properly.

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